Human Papilloma Virus, otherwise known as HPV, is a prevalent sexually transmitted disease in the United States. Is it responsible for cervical cancer? Are there vaccines available against HPV? What are the ethical controversies related to the vaccine?
Human Papilloma Virus, or HPV is a ubiquitous virus in the United States. An estimated 6 million individuals are newly infected annually. Most HPV infections are not only asymptomatic, but they’re too small to be clinically noticeable. Externally, however, infections can be visible as warts.
History of HPV
In the 1950s, at least 15,000 women were dying of cervical cancer every year. Henrietta Lacks was one such woman diagnosed with cervical cancer. However, many women chose not to get tested and Henrietta Lacks was one among them. Henrietta Lacks died in October of 1951, less than a year after her diagnosis. Years later, scientists discovered that her cervical cancer was caused by an infection known as human papillomavirus or HPV.
It was also discovered that these tumor cells of Henrietta were immortal, paving the way for study of genes that turn on and off cancer cells and testing different drugs for their efficacy.
This is a transcript from the video series An Introduction to Infectious Diseases. Watch it now, on Wondrium.
Prevalence and Connection to Cervical Cancer
HPV has the highest prevalence rate of 45 percent in girls and women of ages 14 to 26 years and an overall prevalence of 27 percent among this gender. The virus also causes genital warts in one percent of the men. The prevalence gradually declines with increasing age since 90 percent of new HPV infections actually regress over 6 to 18 months.
The most important concern about the infection is that it is implicated in more than 99 percent of cervical cancers. Cervical cancer is one of the top ten causes of female cancer mortality.
Persistent infection is a prerequisite for progression to cervical cancer. Of the over hundred types of HPV, there are about 13 types that can cause cervical cancer.
About 70 percent of the cervical cancer cases are caused by genotypes 16 and 18, while 90 percent of genital warts are caused by genotypes 6 and 11. It was only in 1984 that the HPV 18 strain of the virus, which Henrietta Lacks had, was actually discovered. These are the types that are targeted in vaccination.
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The Cancer Causing Mechanism
The HPV DNA can insert itself into the DNA of the host cell. HPV has the potential to cause oncogenes, which lead the host cell to develop malignant characteristics. In addition, it is also responsible for 5 percent of all cancers in the world, including throat and anal cancer, in both men and women.
A Pap smear test of the cervix is used to screen women for cervical cancer. It is ideal to screen for cervical cancer once in every three years. Nevertheless, there are more new and sophisticated molecular diagnostic tests to look for the higher-risk variants of HPV that are associated with cancerous transformation, which may eventually replace the Pap smear.
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Vaccinations for HPV Infections
Vaccines are usually immunogenic for the creation of antibodies to protect against chronic HPV infection. Immunity is thought to last for at least 10 years and, at the present time, no booster vaccination is recommended.
The vaccine needs to be administered before exposure to HPV infections since there is no protection from HPV disease for infections acquired before vaccination.
The FDA approved a vaccine for use in females of age 9 to 26 in 2006. This vaccine offers protection from infection for HPV genotypes 6, 11, 16, and 18, which cause the most incidences of cervical cancer and genital warts. A second HPV vaccine was also approved in 2009, but contains only genotypes 16 and 18.
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Vaccine and the Ethical Question
National organizations are targeting girls, age 11 to 12 years old, but also recommend vaccination of women ages 13 to 26 since this age group is still at risk. Naturally, this youthful age of vaccination has generated some ethical controversy.
Some parents are likely to object to giving a vaccine against a STD before the child was sexually active. Conservative religious groups strongly opposed a mandate, arguing it would condone premarital sex and undermine parental rights.
In spite of these potential objections, vaccine committees have also recommended that boys and young men also receive the vaccine. This is based on the hypothesis that vaccination would contribute to reduced HPV prevalence among men and, therefore, reduced transmission to their sexual partners.
Common Questions about HPV and Cervical Cancer
Most HPV infections are not only asymptomatic, but they’re also too small to be clinically noticeable. Externally, however, infections can be visible as warts.
A Pap smear test of the cervix is used to screen women for cervical cancer. There are also more new and sophisticated molecular diagnostic tests to look for the higher-risk variants of HPV, which may eventually replace the Pap smear.
The FDA approved an HPV vaccine for use in females of age 9 to 26 that offers protection from infection for HPV genotypes 6, 11, 16, and 18. A second HPV vaccine that contains only genotypes 16 and 18 was approved in 2009.
National organizations target girls in the age group of ages 11 to 12 years old for HPV vaccinations. This youthful age of vaccination has generated some ethical controversy as parents and conservative groups object to giving a vaccine before the child was sexually active, condone premarital sex and undermine parental rights.